Final answer:
Procter & Gamble (P&G) made history in 1911 by becoming the first company to sponsor a radio serial drama, 'The New World Symphony', as an advertising strategy.
Step-by-step explanation:
The correct answer is C) 1911 in Cincinnati. In 1911, Procter & Gamble (P&G) made history by becoming the first advertiser to sponsor a radio serial drama called 'The New World Symphony'. This marked a significant milestone in advertising history as it was the first time a company used radio to promote their products. The event took place in Cincinnati, Ohio, where P&G is headquartered.